Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Boiling and Evaporation
Name: Elanggovan K.
Status: student
Age: 13
Location: N/A
Country: N/A
Date: 5/13/2003


Question:
What is the difference between boiling and evaporation?


Replies:
Evaporation is a more general term. Evaporation means to change of a liquid into a vapor (gas). It does not matter what the vapor pressure of the substance is. Water at 25 C has a vapor pressure of about 25mm Hg. If a stream of dry air passes over the surface of the water it will evaporate. Eventually there will be no liquid water remaining. On the other hand, "boiling" usually refers to the temperature where the vapor pressure is 1 atmosphere = 760 mm Hg. In the case of water this temperature is 100 C.

Vince Calder


Elanggovan K,

Depending on the conditions that produce them, in both processes molecules in the liquid state are moved into the gaseous state. Evaporation is traditionally looked upon as the slower, relatively quiescent case occurring at or near ambient temperature. Boiling, (a visually more vigorous process) implies some externally applied heat source to speed up the evaporative mechanism. Even so, the fundamental movement of liquid-to-the-vapor-state is essentially the same.

Regards,
ProfHoff 665



Click here to return to the Chemistry Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory